Select a circular section from the marshmallow source. Duplicate it 4 times, resize, transform and warp it to create the body shapes of olaf. Adjust colors.
Make head with more marshmallow sections. Make nose from carrot source. Make eyes from planet source. Make tooth from teeth source. Trace a round inside mouth area with lasso tool. Copy and paste the selected area and darken the area using multiply mode.
Make pupils and buttons from pebble source. Make arms, eyebrows and hair from tree source. Do some dodge and burn to create shadows and highlights to head and body.
Copy head and body, flip vertically and blend using soft light mode to create a reflection on the ice. Blur the glaciers to create depth of field. Add head and body shadows on ice.
Add snow bokeh source and blend using screen mode.
Add snowflakes and also blend using screen mode.
Adjust lighting, add a bit of pink color to highlights. Lighten center of image using screen. Create a darkened edge by copying a border section, blurring it and blending using multiply mode.